Plenty of pundits have already argued that this program could be really annoying, but if McGeveran is right, it also could violate a law that was instituted to protect people from having their names and likenesses used for advertisements without permission. Specific written consent, he underscored, is necessary. True, it's a state law, but the fact that Social Ads are online, and hence displayed on computers in New York, could get in the way.

"I don't see how broad general consent to share one's information translates into the specific written consent necessary for advertisers to use one's name (and often picture) under this law," McGeveran wrote.

According to Hansell's article in the Times, Facebook's chief privacy officer has already said he thinks McGeveran's interpretation of the law is too broad to apply to Facebook's Social Ads.